The JLPT has five levels: N1, N2, N3, N4 and N5. The easiest level is N5 and the most difficult level is N1.
N5 - The ability to understand some basic Japanese.
N4 - The ability to understand basic Japanese.
N3 - The ability to understand Japanese used in everyday situations to a certain degree.
N2 -
The ability to understand Japanese used in everyday situations, and in a variety of circumstances to a certain degree.
N1 - The ability to understand Japanese used in a variety of circumstances.